Question

arduino I2C传感器及1602液晶显示屏,void变量值带入loop循环的问题

Arduino2560, 想把heading_o的初始值通过指针TT带入到loop循环, 作为一个不变的参照值, 但实际带过来的值却不停的在变化, 且并不是初始值,不知道问题出在哪里, 请大侠指点:

#include <Wire.h>
#include <HMC5883L.h>
#include <math.h>
#include <LiquidCrystal_I2C.h>

HMC5883L compass;

LiquidCrystal_I2C lcd(0x27,16,2); // set the LCD address to 0x20 for a 16 chars and 2 line display

float *TT;

void setup()
{
Serial.begin(9600);
Wire.begin();
compass = HMC5883L();
compass.SetScale(1.3);
compass.SetMeasurementMode(Measurement_Continuous);

lcd.init(); // initialize the lcd
// Print a message to the LCD.
lcd.backlight();
lcd.print("Hello, world!");
delay(3000);

MagnetometerRaw raw = compass.ReadRawAxis();
MagnetometerScaled scaled = compass.ReadScaledAxis();
float xHeading = atan2(scaled.YAxis, scaled.XAxis);
if(xHeading < 0) xHeading += 2*PI;
if(xHeading > 2*PI) xHeading -= 2*PI;

float heading_o;
heading_o1 = xHeading * 180/M_PI-180;
TT=&heading_o;

lcd.setCursor(8,0);
lcd.print(heading_o);

delay(3000);
}

void loop()
{
MagnetometerRaw raw = compass.ReadRawAxis();
MagnetometerScaled scaled = compass.ReadScaledAxis();
float xHeading = atan2(scaled.YAxis, scaled.XAxis);

if(xHeading < 0) xHeading += 2*PI;
if(xHeading > 2*PI) xHeading -= 2*PI;

float xDegrees = xHeading * 180/M_PI;

float heading = xDegrees-180;

Serial.print(xDegrees);
Serial.print(",");

Serial.println(";");
Serial.print(heading);
Serial.println(";____");

lcd.clear();
lcd.print(xDegrees);

lcd.setCursor(8,0);

lcd.print(*TT);

lcd.setCursor(0,1);
lcd.print(heading);

Answer 1

你把TT，heading定义为全局变量，它当然随着heading变化，写一个子函数，用局部变量给全局变量TT赋值。